Photoelectric tube



Patented Nov. 16, 1943 UNITED STATES PATENT OFFICE 12,334,471 frnoToELEo'rRlo wenn Everettn. Bickiey, Balaoynwya, 'Pari `ApplicationJune 7, 1941i, SerialrNo. 397,004

401mm. Cl. 'V250- 165),

The. present invention .l relates j to `electronic tubes and moreparticularly to photo-electric tubes.

In tubes of lthe photo-.electric type it is important that-the tube benot 'only highly sensitive to iight :values but that the sensitivity beof last` ing quality. Also such tubes must be so -confstructedvas to`,avoid internal short circuits orA leakage *.si-nce'these; destroy theeffectiveness of the tube. In tubesas heretofore constructed,

completely attained and Ysensitivi-ty 'is more or less variable whileshort circuits .are of Acommon -occurrence.

Some `ofA the objects of the 'present invention are to provide `animproved photo-electric tube; .to provide a photo-electrictube vwhereinsensitiv- .ity is prolonged .andgthelife of thetube materiallyincreased; to provide a photof-electric tube wherein .the action tendingto :produce a short upon the top of press or other areas locally ad- Pjacent current conductors; yto provide means for heating insulatingparts of .a photo-electric tube which are in close proximity to currentconductors, such vheating-beingy particularly during the di'schargeof4thecapsule or subsequently from exterior means; to provide means toensure a certain and effective contact between the cathode and thecathode lining of the tube; and to provide other improvements as willhereinafter appear. l

In the accompanying drawing Fig. 1 represents a side elevation, partlybroken away, of a photo electric tube embodying one form of the presentinvention; Fig. 2 represents a side elevation on an enlarged scale ofone form `of electrode assembly for the tube showing the anode inlongitudinal section; Fig. 3 represents a sec-v tion on line 3-3 of Fig.2; Fig. 4 represents a detail of the cathode terminal; Fig. 5 representsone of the slider contact members enlarged; and

.lO these. highly desirable features have not been the .respective partsare preferably by welded joints. l a

here shown the anode IB is formed by a metal rod all .supported upon thepress I I and .suspending a metal sleeve 2| fromitsfree end, the rod 2o:forming the axis of the sleeve and being; spaced therefrom. Theattached end of .the sleeve 2l )is closed by crimping the sleeve intocontact with the rod 2i) where it is Welded and thus provides, a `closedend for the tube. The opposite of the sleeve V2I is open and is ,mountedVVveryvclese to the press, ybut not touching it, to restrict theentrance of vapors and prese-nty large. surfaces on which these can con-Fig. 6 represents a section on line 6-6 of Fig. 2.

Referring to the drawing, one form of the present invention comprises anevacuated envelope Il) of generally cylindrical shape including a pressII and base I2 of usual form. The press II carries the terminal wires I3and I4, the former leading from the exteriorprong I5 to the tube anodeI6, and the latter leading from the exterior prong II to the cathodelead-in I8. Connections between the wires I3 and I4, and

dense before they will form a `continuous conducting layer. Therelatively large diameter of thesleeve `2l ,gives-added sensitivity ascompared to the ordinary construction using a small anode. This is duetothe fact that the sleeve gets hot whenjtheltube is being'bombarded andradiates ,heat ,whichl heats the deposit while it is being .formed .onthe glass. A tubular sleeve gets hot- .ter than a wire underbombarding.

'lnkorder to providefa relatively long narrow ,labyrinth passage throughthe sleeve 2I and to reducetthe chance of a short circuit, a glass tube..22 is'supportedon the press of Such diameter as 4"willlflt within themetal sleeve 2l 4and encircle the rodA 2!! withoutr touching either ofthe parts.

For ensuring an effective contact of the cathode lead-in I8 with themetallic coating 23 on the inner wall of the envelope I0, a spring 24 ofhair pin shape is welded to the entering cath-` ode wire I4 and is soadjusted that the fingerlike ends of the spring rest against theenvelope Ill. Each arm of this spring 24 carries a polygonal shapedslider 25 formed of metal and which is free to ride along the spring armupon which it is mounted. When the electrode assembly is inserted`within the envelope Il), prior to evacuation and prior to coating theenvelope,the sliders 25 are positioned near the welded end of the springso that each is out of Contact with the envelope and so remains untilafter the coating 23 has been applied. To bring the slider or sliders 25into contact with the coating 23, the outer end of the envelope I0 isbumped in such a manner as to cause the sliders 25 to travel along thespring arms and nally bite into the coating where each is held by thespring action, and a good contact maintained indenitely.

For producing a uniform coating upon the wall of the envelope, a capsuleor pellet 2S, of any composition well known to the art, which releasescondensable vapors upon being heated, is mounted upon a metal base plate21 supported from the cathode lead-in I8 transversely of the envelope ata point relatively close to the press Il and also near the longitudinalaxis of the envelope. This plate 21 becomes heated during the bombardingof the capsule and radiates heat to the press so that the latter becomeshot and prevents deposition of the cathode vapors thereon. A port 28 inthe pocket 30 of the plate 21 serves to release the vapor upwardly intolthe envelope l0. The plate 21 is opposite the press Il while the portthrough Whichv the capsule discharges faces the interior of the tube,thus the surface. j

and hence local heating by radiant energy is,

greatly reduced. However the face of the plate 21 juxtaposed to thepress Il is of considerable area and the radiant heat thereof now servesa useful purpose in that it keeps the press so hot Having thus describedmy invention, I claim:

1. A photo-electric tube comprising a glass envelope and an electrodeassembly therein including a press, an anode, a photo-cathode and acathode lead-in carried by said press, and conductor Wires leadingrespectively from said anode and cathode lead-in to the exterior of saidenvelope, a capsule to release vapor When heated to form saidphoto-cathode on the inside of said envelope, a plate of heat-conductingmaterial mounted in close proximity to said press whereby when heatedsaid plate radiates heat to said Vpress to prevent condensation of saidvapor on said press, and an area of graphitic composition on said plateto supplement the action of the heat in deposit prevention.

2. A photoelectric tube comprising a'glass r` envelope and an electrodeassembly therein including aV press, an anode, a photo-cathode and acathode lead-in carried by saidpress, said anode l being formed of aconducting rod, a sleeve'of conducting material connected to and'encircling that it is left-very clear when the tube is complete. Hencethe time required to form any conductive lm is greatly increased and thedanger of short circuits thereby reduced to a minimum. As a furthermeans to delaythe formation of a conducting film on the press a portionof the face vof the plate 21 can be coated with some material vfor thevapor results in a verylong life of the tube. The metal sleeve 2|,especially when blackened, maintains itself at a higher temperature whenin the path of radiant energy thereby retarding the tendency of vaporstoenter the tube and increasing the elciency as compared to tubes usingthe glass boot alone,

said rod, and a tube of insulating material between said rod.` andsleeve forming anannular passage within said sleeve, andY conductingwires leading respectively from said anode and vcathode'lead-i'n carriedbysaid press, said anode being 'formed by a glass' tube, a rod passingaxially through said tube, a metal sleeve of cap form suspended by saidrod about said tube, and a coatin'g'on said sleeve to retard the depositof cathode Vapor inthe vicinity of said vanode to prevent shortcircuits, and conducting wires leading respectively from said anodeandcathode to the exterior' of said envelope.

4. A photo-electric -tube `comprising va glass envelopel andan electrodeassembly'therein including a press, 'ananode and a cathodelead-incarried by said press, said cathode lead-in termi'- nating ina springarm, a'cathode deposit on the interior `of said envelope and a metalslider mounted on said arm and pressed by `.said arm Aintocontact withsaid cathode deposit on said envelope.v EVERETT H. BICKLEY.

